CN110295972B - Exhaust gas purification system for internal combustion engine - Google Patents

Exhaust gas purification system for internal combustion engine Download PDF

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Publication number
CN110295972B
CN110295972B CN201910220337.6A CN201910220337A CN110295972B CN 110295972 B CN110295972 B CN 110295972B CN 201910220337 A CN201910220337 A CN 201910220337A CN 110295972 B CN110295972 B CN 110295972B
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exhaust gas
irradiation
predetermined
gas purification
temperature
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CN110295972A (en
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小桥贤一
大月宽
菊地和希
池田慎治
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Toyota Motor Corp
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Toyota Motor Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/66—Regeneration of the filtering material or filter elements inside the filter
    • B01D46/80—Chemical processes for the removal of the retained particles, e.g. by burning
    • B01D46/84—Chemical processes for the removal of the retained particles, e.g. by burning by heating only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9495—Controlling the catalytic process
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/027—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using electric or magnetic heating means
    • F01N3/028—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using electric or magnetic heating means using microwaves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
    • F01N3/202—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means using microwaves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/005—Electrical control of exhaust gas treating apparatus using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6435—Aspects relating to the user interface of the microwave heating apparatus
    • H05B6/6438—Aspects relating to the user interface of the microwave heating apparatus allowing the recording of a program of operation of the microwave heating apparatus
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • H05B6/645—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using temperature sensors
    • H05B6/6452—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using temperature sensors the sensors being in contact with the heated product
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/66—Circuits
    • H05B6/68—Circuits for monitoring or control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2279/00—Filters adapted for separating dispersed particles from gases or vapours specially modified for specific uses
    • B01D2279/30—Filters adapted for separating dispersed particles from gases or vapours specially modified for specific uses for treatment of exhaust gases from IC Engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
    • F01N2260/04—Exhaust treating devices having provisions not otherwise provided for for regeneration or reactivation, e.g. of catalyst
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/025—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting O2, e.g. lambda sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/14—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics having more than one sensor of one kind
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1404—Exhaust gas temperature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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  • Biomedical Technology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

The invention provides an exhaust gas purification system for an internal combustion engine, which can better inhibit the reduction of the detection accuracy of an exhaust gas sensor caused by the influence of electromagnetic waves in the exhaust gas purification system for the internal combustion engine irradiating the electromagnetic waves to an exhaust gas purification device arranged in an exhaust passage of the internal combustion engine. In an exhaust gas purification system for an internal combustion engine in which an exhaust gas sensor is disposed in an irradiation range of an electromagnetic wave of an irradiation device that irradiates the exhaust gas purification device with an electromagnetic wave of a predetermined frequency, even when a predetermined irradiation execution condition is satisfied, irradiation of the electromagnetic wave from the irradiation device is stopped during a sampling period in which an output value of the exhaust gas sensor is sampled.

Description

Exhaust gas purification system for internal combustion engine
Technical Field
The present invention relates to an exhaust gas purification system for an internal combustion engine.
Background
There is known a technique of irradiating an electromagnetic wave to an exhaust gas purification apparatus provided in an exhaust passage of an internal combustion engine. For example, patent document 1 discloses a technique of raising the temperature of an exhaust purification catalyst provided in an exhaust passage of an internal combustion engine by irradiating the exhaust purification catalyst with microwaves from a microwave irradiation device. Patent document 2 discloses a technique of irradiating a microwave to a particulate filter provided in an exhaust passage of an internal combustion engine and collecting particulate matter in exhaust gas. In the configuration described in patent document 2, microwaves are irradiated to the upstream end surface of the particulate filter. A temperature sensor is provided in the exhaust passage on the downstream side of the particulate filter.
[ Prior Art document ]
[ patent document ]
[ patent document 1 ] Japanese patent laid-open publication No. 2017-02785
[ patent document 2 ] Japanese patent application laid-open No. 4-171210
As described above, in the exhaust passage of the internal combustion engine, an electromagnetic wave may be irradiated from the irradiation device to the exhaust gas purification device such as the exhaust gas purification catalyst or the particulate filter. On the other hand, an exhaust gas sensor such as a temperature sensor or an air-fuel ratio sensor may be provided in the exhaust passage at a position relatively close to the exhaust gas purification device. At this time, if the exhaust gas sensor is disposed in the exhaust passage within the irradiation range of the electromagnetic wave of the irradiation device, the electromagnetic wave also reaches the exhaust gas sensor when the exhaust gas purification device is irradiated with the electromagnetic wave from the irradiation device. In this case, the electromagnetic wave may affect the output value of the exhaust gas sensor. That is, an error may occur in the output value of the exhaust gas sensor due to the influence of the electromagnetic wave. Therefore, the detection accuracy of the exhaust gas sensor may be degraded.
Here, in order to avoid the influence of the electromagnetic wave on the output value of the exhaust gas sensor, it is conceivable to provide the exhaust gas sensor at a position out of the irradiation range of the electromagnetic wave in the exhaust passage. However, depending on the detection target of the exhaust gas sensor, the degree of freedom of the installation position of the exhaust gas sensor is low, and the exhaust gas sensor may have to be installed in the irradiation range of the electromagnetic wave. In order to avoid the influence of the electromagnetic wave on the output value of the exhaust gas sensor, it is also conceivable to provide a shield member for shielding the electromagnetic wave in the exhaust gas sensor. However, when such a shield member is provided, contact between the exhaust gas sensor and the exhaust gas is hindered by the shield member, and as a result, there is a possibility that the responsiveness of the exhaust gas sensor is lowered.
Disclosure of Invention
The present invention has been made in view of the above-described problems, and an object of the present invention is to more favorably suppress a decrease in detection accuracy of an exhaust gas sensor due to the influence of electromagnetic waves in an exhaust gas purification system of an internal combustion engine that irradiates an exhaust gas purification device provided in an exhaust passage of the internal combustion engine with electromagnetic waves.
The invention temporarily stops irradiation of electromagnetic waves to an exhaust gas purification device during a sampling period in which an output value of an exhaust gas sensor is sampled.
More specifically, an exhaust purification system for an internal combustion engine includes: an exhaust gas purification device provided in an exhaust passage of an internal combustion engine; an irradiation device that is provided in the exhaust passage and irradiates the exhaust gas purification device with electromagnetic waves of a predetermined frequency; an exhaust gas sensor disposed in the exhaust passage within an irradiation range of the electromagnetic wave of the irradiation device; and an irradiation control unit that performs irradiation of the electromagnetic wave from the irradiation device when a predetermined irradiation execution condition is satisfied, and stops the irradiation of the electromagnetic wave from the irradiation device during a sampling period in which the output value of the exhaust gas sensor is sampled even when the predetermined irradiation execution condition is satisfied.
In the exhaust gas purification system of the present invention, an irradiation device that irradiates the exhaust gas purification device with electromagnetic waves of a predetermined frequency is provided in the exhaust passage. Here, the predetermined frequency is a value set according to the purpose of irradiation of the electromagnetic wave, and is determined based on an experiment or the like. The irradiation control means performs irradiation of the electromagnetic wave from the irradiation device when a predetermined irradiation execution condition is satisfied. Here, the predetermined irradiation execution condition is set according to the irradiation purpose of the electromagnetic wave.
In the exhaust gas purification system according to the present invention, the exhaust gas sensor is disposed in the exhaust passage in the range of irradiation of the electromagnetic wave by the irradiation device. Therefore, when the electromagnetic wave is irradiated from the irradiation device, the electromagnetic wave also reaches the exhaust gas sensor. The exhaust gas sensor is a sensor that outputs an output value corresponding to a value of a predetermined parameter that is a detection target, which is a parameter related to the state of the exhaust gas, such as the temperature of the exhaust gas or the concentration of a predetermined component in the exhaust gas.
In the present invention, the irradiation control means stops the irradiation of the electromagnetic wave from the irradiation device during the sampling period in which the output value of the exhaust gas sensor is sampled even when the predetermined irradiation execution condition is satisfied. Here, the sampling period is a period for acquiring an output value of the exhaust gas sensor as a detection value relating to a predetermined parameter that is a detection target of the exhaust gas sensor. According to the present invention, during sampling, the electromagnetic wave does not reach the exhaust gas sensor. Therefore, during sampling, the influence of the electromagnetic wave on the output value of the exhaust gas sensor can be suppressed. Therefore, during the sampling period, the output value of the exhaust gas sensor that is not affected by the electromagnetic wave can be acquired as the detection value detected by the exhaust gas sensor. Further, since it is not necessary to provide a shield member for shielding electromagnetic waves to the exhaust gas sensor, it is possible to prevent the exhaust gas sensor from being hindered from contacting the exhaust gas, thereby preventing the exhaust gas sensor from being deteriorated in response. Therefore, the deterioration of the detection accuracy of the exhaust gas sensor due to the influence of the electromagnetic wave can be more favorably suppressed.
In the present invention, the irradiation control means may stop irradiation of the electromagnetic wave from the irradiation device before the start of the sampling period, and restart irradiation of the electromagnetic wave from the irradiation device after the end of the sampling period. Thus, the irradiation stop period of the electromagnetic wave from the irradiation device is longer than the sampling period. Therefore, even if the timing of stopping the irradiation of the electromagnetic wave or the timing of restarting the irradiation of the electromagnetic wave varies due to a variation in the control of the irradiation device or the like, it is possible to suppress the electromagnetic wave from reaching the exhaust gas sensor with a higher probability during the sampling period.
In addition, in an exhaust gas purification system for an internal combustion engine, sampling of an output value of an exhaust gas sensor may be repeatedly performed at a predetermined sampling cycle. At this time, when the irradiation of the electromagnetic wave from the irradiation device is stopped every sampling period, the irradiation of the electromagnetic wave is also repeatedly stopped. As a result, the time for achieving the purpose of irradiating the exhaust gas purifying device with electromagnetic waves may be delayed.
Therefore, in the present invention, when the sampling of the output value of the exhaust gas sensor is repeatedly performed at a predetermined sampling period, the predetermined sampling period may be set longer in a state where the length of the sampling period is made the same when the predetermined irradiation execution condition is satisfied than when the predetermined irradiation execution condition is not satisfied. Thus, when the irradiation of the electromagnetic wave from the irradiation device is performed, the interval between the sampling period and the next sampling period becomes longer than when the irradiation of the electromagnetic wave is not performed. Therefore, even when the predetermined irradiation execution condition is satisfied, the frequency of stopping irradiation of the electromagnetic wave from the irradiation device can be reduced as compared with the case where the sampling period is the same as when the predetermined irradiation execution condition is not satisfied. Therefore, delay in the time to achieve the purpose of irradiating the exhaust gas purification device with electromagnetic waves can be suppressed.
In the present invention, when the sampling of the output value of the exhaust gas sensor is repeatedly performed at a predetermined sampling cycle when a predetermined irradiation execution condition is satisfied, the irradiation control means may stop the irradiation of the electromagnetic wave from the irradiation device in one sampling period of a predetermined plurality of sampling periods. This makes it possible to reduce the frequency of stopping the irradiation of the electromagnetic wave from the irradiation device, as compared with the case where the irradiation of the electromagnetic wave from the irradiation device is stopped every sampling period. Therefore, delay in the time to achieve the purpose of irradiating the exhaust gas purification device with electromagnetic waves can be suppressed. In addition, the influence of the electromagnetic wave on the output value of the exhaust gas sensor can be suppressed in the one-time sampling period in which the irradiation of the electromagnetic wave from the irradiation device is stopped among the predetermined multiple sampling periods. That is, when sampling of the output value of the exhaust gas sensor is performed a predetermined plurality of times during the execution of irradiation of the electromagnetic wave from the irradiation device, the output value of the exhaust gas sensor not affected by the electromagnetic wave can be acquired as the detection value detected by the exhaust gas sensor during one of the sampling periods.
In the present invention, the exhaust gas sensor may be a temperature sensor that detects the temperature of the exhaust gas flowing into the exhaust gas purification apparatus (hereinafter, also referred to as "inflow exhaust gas") or the exhaust gas flowing out from the exhaust gas purification apparatus (hereinafter, also referred to as "outflow exhaust gas"). A temperature sensor that detects the temperature of the inflowing exhaust gas or the temperature of the outflowing exhaust gas needs to be provided in the exhaust passage at a position near the exhaust gas purification device. Therefore, such a temperature sensor sometimes has to be provided within the irradiation range of the electromagnetic wave. According to the present invention, even when such a temperature sensor is provided within the irradiation range of electromagnetic waves, it is possible to more favorably suppress a decrease in the detection accuracy of the temperature sensor due to the influence of electromagnetic waves.
Effects of the invention
According to the present invention, in an exhaust purification system of an internal combustion engine that irradiates an exhaust purification device provided in an exhaust passage of the internal combustion engine with electromagnetic waves, it is possible to more favorably suppress a decrease in detection accuracy of an exhaust sensor due to the influence of the electromagnetic waves.
Drawings
Fig. 1 is a diagram showing a schematic configuration of an intake system and an exhaust system of an internal combustion engine according to an embodiment.
Fig. 2 is a time chart showing changes in the sampling flag, the irradiation execution flag, the output value Sout1 of the first temperature sensor, and the output value Sout2 when the predetermined irradiation execution condition for executing microwave irradiation from the irradiation device to the filter is satisfied according to the embodiment.
Fig. 3 is a flowchart showing a control flow of microwave irradiation from the irradiation device to the filter according to the embodiment.
Fig. 4 is a time chart showing transitions of the sampling flag, the irradiation execution flag, the output value Sout1 of the first temperature sensor, and the output value Sout2 of the second temperature sensor when the predetermined irradiation execution condition of the first modification is satisfied.
Fig. 5 is a time chart showing transition of the sampling flag, the irradiation execution flag, and the filter temperature when the predetermined irradiation execution condition is satisfied in the second modification.
Fig. 6 is a time chart showing transitions of the sampling flag, the irradiation execution flag, the output value Sout1 of the first temperature sensor, and the output value Sout2 of the second temperature sensor when the predetermined irradiation execution condition is satisfied in the third modification.
Description of the reference numerals
1. internal combustion engine
3. exhaust passage
8. particulate filter
9. irradiation apparatus
10··ECU
13. first temperature sensor
14 second temperature sensor
Detailed Description
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the present invention to these unless otherwise specified.
< example >
(schematic structure)
Fig. 1 is a diagram showing a schematic configuration of an intake system and an exhaust system of an internal combustion engine according to the present embodiment. The internal combustion engine 1 is a diesel engine for driving a vehicle. However, the internal combustion engine of the present invention is not limited to the diesel engine, and may be a gasoline engine. The internal combustion engine 1 is provided with fuel injection valves 6 for respective cylinders. An intake passage 2 and an exhaust passage 3 are connected to the internal combustion engine 1. An airflow meter 4 and a throttle valve 5 are provided in the intake passage 2. The airflow meter 4 detects the flow rate of intake air (i.e., the intake air amount of the internal combustion engine 1). The throttle valve adjusts the intake air amount of the internal combustion engine 1 by changing the cross-sectional area of the intake air flow path.
An oxidation catalyst 7 and a particulate filter (hereinafter referred to as "filter") 8 are provided in the exhaust passage 3. In the exhaust passage 3, a filter 8 is provided downstream of the oxidation catalyst 7. The filter 8 is a wall-flow type filter that traps Particulate Matter (hereinafter referred to as "PM") in the exhaust gas. A first temperature sensor 13 is provided in the exhaust passage 3 on the downstream side of the oxidation catalyst 7 and on the upstream side of the filter 8, and a second temperature sensor 14 is provided in the exhaust passage 3 on the downstream side of the filter 8. The first temperature sensor 13 is a sensor for detecting the temperature of the exhaust gas flowing into the filter 8 (inflow exhaust gas), and the second temperature sensor 14 is a sensor for detecting the temperature of the exhaust gas flowing out of the filter 8 (outflow exhaust gas). That is, the parameter to be detected by the first temperature sensor 13 is the temperature of the inflowing exhaust gas, and the parameter to be detected by the second temperature sensor 14 is the temperature of the outflowing exhaust gas. Therefore, the first temperature sensor 13 and the second temperature sensor 14 are disposed at positions near the filter 8.
Further, an irradiation device 9 is provided in the exhaust passage 3 on the downstream side of the oxidation catalyst 7 and on the upstream side of the first temperature sensor 13. The irradiation device 9 is a device that irradiates the filter 8 with microwaves that are electromagnetic waves. The irradiation device 9 includes a microwave oscillator and a microwave radiator (both not shown). A semiconductor oscillator may be used as the microwave oscillator. The irradiation device 9 emits the microwaves generated by the microwave oscillator from the microwave radiator toward the filter 8.
Here, the first temperature sensor 13 is disposed between the irradiation device 9 and the filter 8 in the exhaust passage 3. The second temperature sensor 14 is disposed in the exhaust passage 3 on the downstream side of the filter 8, but in the vicinity of the filter 8. Therefore, the positions where the first temperature sensor 13 and the second temperature sensor 14 are disposed are within the irradiation range of the microwave of the irradiation device 9 in the exhaust passage 3. That is, when the filter 8 is irradiated with microwaves from the irradiation device 9, the microwaves also reach the first temperature sensor 13 and the second temperature sensor 14.
In the present embodiment, the filter 8 corresponds to the "exhaust gas purification apparatus" of the present invention. However, the exhaust gas purifying apparatus of the present invention is not limited to the particulate filter, and may be an exhaust gas purifying catalyst (an oxidation catalyst, a three-way catalyst, an NOx storage reduction catalyst, an NOx selective reduction catalyst, or the like). Further, the exhaust gas purifying apparatus of the present invention may be configured by combining a particulate filter and an exhaust gas purifying catalyst. In the present embodiment, the irradiation device 9 corresponds to the "irradiation device" of the present invention.
In the present embodiment, the first temperature sensor 13 and/or the second temperature sensor 14 correspond to the "exhaust gas sensor" of the present invention. However, the exhaust gas sensor of the present invention is not limited to the temperature sensor, and may be a sensor (O) that detects a parameter other than temperature relating to the state of the exhaust gas, such as the concentration of a predetermined component in the exhaust gas2Sensors, NOx sensors, air-fuel ratio sensors, etc.).
An Electronic Control Unit (ECU)10 is also provided in the internal combustion engine 1. The ECU10 controls the operating state of the internal combustion engine 1 and the like. Airflow meter 4, first temperature sensor 13, and second temperature sensor 14 are electrically connected to ECU 10. A crank position sensor 11 and an accelerator opening degree sensor 12 are electrically connected to the ECU 10. The detection values of the sensors are input to the ECU 10. The ECU10 derives the engine rotational speed of the internal combustion engine 1 based on the detection value of the crank position sensor 11. The ECU10 derives the engine load of the internal combustion engine 1 based on the detection value of the accelerator opening sensor 12.
In the present embodiment, during the operation of the internal combustion engine 1, the ECU10 repeatedly performs sampling of the output value of the first temperature sensor 13 and the output value of the second temperature sensor 14 at predetermined sampling cycles. That is, the ECU10 repeats sampling periods in which the output value of the first temperature sensor 13 is acquired as the detected value of the temperature of the inflowing exhaust gas and the output value of the second temperature sensor 14 is acquired as the detected value of the outflowing exhaust gas at predetermined sampling cycles. The ECU10 estimates the temperature of the filter 8 based on the temperature of the inflowing exhaust gas and the temperature of the outflowing exhaust gas acquired during the sampling period. Note that the length of one sampling period is predetermined (for example, 10 msec).
Further, the throttle valve 5, the fuel injection valve 6, and the irradiation device 9 are electrically connected to the ECU 10. And, these devices are controlled by the ECU 10. For example, when there is a request for heating the filter 8, the ECU10 irradiates the filter 8 with microwaves of a predetermined frequency from the irradiation device 9. The predetermined frequency at this time is determined based on experiments or the like as a frequency preferable for heating the filter 8.
(microwave irradiation)
Here, the collected PM is gradually accumulated in the filter 8. Therefore, during the operation of the internal combustion engine 1, the ECU10 estimates the amount of PM collected by the filter 8 and the amount of PM oxidized in the filter 8, respectively, and integrates these values to calculate the PM accumulation amount in the filter 8 as needed. When the PM accumulation amount in the filter 8 reaches a predetermined regeneration start threshold value, the temperature of the filter 8 is forcibly increased to a temperature at which PM can be oxidized (PM oxidation temperature), and thereby the filter regeneration process for oxidizing the PM accumulated in the filter 8 is executed. In the present embodiment, the filter regeneration process is realized by microwave irradiation from the irradiation device 9.
Specifically, when the PM accumulation amount in the filter 8 reaches a predetermined regeneration start threshold value, the ECU10 starts microwave irradiation of a predetermined frequency from the irradiation device 9 to the filter 8. Thereby, the filter 8 is heated, and the temperature of the filter 8 rises to a predetermined PM oxidation temperature. Then, the ECU10 controls the microwave irradiation from the irradiation device 9 so that the temperature of the filter 8 becomes equal to or higher than a predetermined PM oxidation temperature and so that the temperature is maintained at a temperature near the predetermined PM oxidation temperature. Specifically, the ECU10 stops the microwave irradiation from the irradiation device 9 when the temperature of the filter 8 becomes equal to or higher than the predetermined PM oxidation temperature, and then restarts the microwave irradiation from the irradiation device 9 if the temperature of the filter 8 is lower than the predetermined PM oxidation temperature. That is, in the present embodiment, when the execution condition of the filter regeneration process is satisfied and the temperature of the filter 8 is lower than the predetermined PM oxidation temperature, the ECU10 determines that the heating request for the filter 8 is present and executes the microwave irradiation from the irradiation device 9 to the filter 8.
Here, as described above, in the configuration of the present embodiment, since the first temperature sensor 13 and the second temperature sensor 14 are disposed within the irradiation range of the irradiation device 9, when the microwave of the predetermined frequency is irradiated from the irradiation device 9 toward the filter 8, the microwave also reaches the first temperature sensor 13 and the second temperature sensor 14. When the microwaves reach the first temperature sensor 13 and the second temperature sensor 14, the microwaves may affect the output values of the sensors 13 and 14. That is, an error may occur in the output value of the first temperature sensor 13 and/or the second temperature sensor 14 due to the influence of the microwave. When the output value in the state where the error occurs is sampled as the detection values of the sensors 13 and 14, the detection accuracy of the temperature of the inflow exhaust gas or the temperature of the outflow exhaust gas detected by the sensors is lowered. In this case, the accuracy of the ECU10 in estimating the temperature of the filter 8 also decreases.
Therefore, in the present embodiment, in order to suppress a decrease in the detection accuracy of the temperature of the inflowing exhaust gas detected by the first temperature sensor 13 and the detection accuracy of the temperature of the outflowing exhaust gas detected by the second temperature sensor 14, the irradiation of microwaves from the irradiation device 9 to the filter 8 is stopped during the sampling period in which the output values of the first temperature sensor 13 and the second temperature sensor 14 are sampled. Fig. 2 is a time chart showing transition of the sampling flag, the irradiation execution flag, the output value of the first temperature sensor, and the output value of the second temperature sensor when the predetermined irradiation execution condition for executing microwave irradiation from the irradiation device to the filter is satisfied according to the present embodiment. The predetermined irradiation execution condition in the present embodiment is a condition that the execution condition of the filter regeneration process is satisfied and the temperature of the filter 8 is lower than the predetermined PM oxidation temperature. In fig. 2, the horizontal axis represents time t.
The sampling flag in fig. 2 is a flag that is turned on when the ECU10 samples the output values of the first temperature sensor 13 and the second temperature sensor 14. That is, in fig. 2, a period ds during which the sampling flag is on represents a sampling period. In fig. 2, a period Cs from the start timing of the sampling period ds to the start timing of the next sampling period ds represents a predetermined sampling cycle of the present embodiment.
The irradiation execution flag in fig. 2 is a flag that is turned on when the ECU10 executes irradiation with microwaves of a predetermined frequency from the irradiation device 9. That is, the irradiation of the microwave from the irradiation device 9 is performed while the irradiation execution flag is on, and the irradiation of the microwave from the irradiation device 9 is stopped while the irradiation execution flag is off. Furthermore, Sout1 in fig. 2 represents the output value of the first temperature sensor 13. Furthermore, Sout2 in fig. 2 represents the output value of the second temperature sensor 14. Here, in fig. 2, a line L1 represents the actual temperature of the inflowing exhaust gas to be detected by the first temperature sensor 13. Here, the actual temperature of the inflowing exhaust gas substantially changes. In fig. 2, a line L2 represents the actual temperature of the outflowing exhaust gas to be detected by the second temperature sensor 14. When the filter 8 is irradiated with microwaves of a predetermined frequency from the irradiation device 9, the temperature of the filter 8 rises. Here, the actual temperature of the outflowing exhaust gas (L2) gradually increases with the increase in the temperature of the filter 8.
As shown in fig. 2, when the irradiation execution flag is turned on, the output value Sout1 of the first temperature sensor 13 fluctuates, and an error occurs between the output value Sout1 and the actual temperature of the inflowing exhaust gas. When the irradiation execution flag is turned on, the output value Sout2 of the second temperature sensor 14 fluctuates, and an error occurs between the output value Sout2 and the actual temperature of the outflowing exhaust gas. Such a variation in the output values of the first temperature sensor 13 and the second temperature sensor 14 occurs due to the fact that the microwave irradiated from the irradiation device 9 also reaches these sensors 13 and 14.
However, in the present embodiment, even when a predetermined irradiation execution condition is satisfied, the irradiation execution flag is off in the sampling period ds. That is, in the sampling period ds, the irradiation of the microwave from the irradiation device 9 is stopped. Thus, in the sampling period ds, the microwaves do not reach the first temperature sensor 13 and the second temperature sensor 14. Therefore, in the sampling period ds, the influence of the microwaves on the output values of the first temperature sensor 13 and the second temperature sensor 14 can be suppressed. That is, in the sampling period ds, the occurrence of fluctuations in the output values of the first temperature sensor 13 and the second temperature sensor 14, which are observed during the irradiation of the microwaves from the irradiation device 9, can be suppressed. Therefore, as shown in fig. 2, in the sampling period ds, the output value of the first temperature sensor 13 represents the actual temperature of the inflowing exhaust gas (L1), and the output value of the second temperature sensor 14 represents the actual temperature of the outflowing exhaust gas (L2).
In this way, by stopping the irradiation of the microwaves from the irradiation device 9 during the sampling period, the output value of the first temperature sensor 13 (i.e., the output value corresponding to the actual temperature of the inflowing exhaust gas) and the output value of the second temperature sensor 14 (i.e., the output value corresponding to the actual temperature of the outflowing exhaust gas) which are not affected by the microwaves can be obtained as the detection values detected by the respective sensors 13 and 14. Therefore, it is possible to suppress a decrease in the detection accuracy of the temperature of the inflowing exhaust gas detected by the first temperature sensor 13 and the detection accuracy of the temperature of the outflowing exhaust gas detected by the second temperature sensor 14. As a result, the ECU10 can estimate the temperature of the filter 8 based on the temperature of the inflowing exhaust gas and the temperature of the outflowing exhaust gas detected with high accuracy. Therefore, a decrease in the accuracy of the temperature estimation of the filter 8 detected by the ECU10 can be suppressed.
Further, according to the above, it is also not necessary to provide a shielding member for shielding the microwave to the first temperature sensor 13 and the second temperature sensor 14 in order to suppress the influence of the microwave on the output value of the sensors. Therefore, it is possible to prevent the first temperature sensor 13 and the second temperature sensor 14 from being hindered by the shield member from contacting the exhaust gas, and to prevent the sensors from being deteriorated in response.
(microwave irradiation control flow)
Fig. 3 is a flowchart showing a control flow of microwave irradiation from the irradiation device to the filter according to the present embodiment. This routine is stored in the ECU10 in advance, and is repeatedly executed at predetermined intervals during the operation of the internal combustion engine 1 by the ECU 10. The ECU10 that executes the present routine corresponds to the "irradiation control means" of the present invention.
In the present flow, first, in S101, it is determined whether or not a predetermined irradiation execution condition is satisfied. As described above, the predetermined irradiation execution condition is a condition that the execution condition of the filter regeneration process is satisfied and the temperature of the filter 8 is lower than the predetermined PM oxidation temperature.
Note that, in the ECU10, the amount of PM deposited on the filter 8 is calculated as needed by repeating a process different from the present process at predetermined intervals. When the PM accumulation amount in the filter 8 reaches a predetermined regeneration start threshold, it is determined that the execution condition of the filter regeneration process is satisfied. Then, when the PM accumulation amount in the filter 8 decreases to a predetermined regeneration completion threshold after the execution of the filter regeneration process is started, it is determined that the execution condition of the filter regeneration process is not satisfied. Therefore, the period from when the PM accumulation amount in the filter 8 reaches the predetermined regeneration start threshold to when the PM accumulation amount decreases to the predetermined regeneration completion threshold becomes a period in which the execution condition of the filter regeneration process is satisfied. As described above, the ECU10 estimates the temperature of the filter 8 at any time based on the detected value of the temperature of the inflowing exhaust gas (the output value of the first temperature sensor 13) and the detected value of the temperature of the outflowing exhaust gas (the output value of the second temperature sensor 14) acquired at predetermined sampling intervals.
When an affirmative determination is made in S101, next, in S102, it is determined whether or not the sampling flag is on. If a negative determination is made in S102, that is, if the current period is not the sampling period, then in S103, the irradiation execution flag is on. Thereby, irradiation of the microwave of the predetermined frequency from the irradiation device 9 is performed. When a negative determination is made in S102 even in the case where the present flow is executed in the upward direction, the irradiation of the microwave of the predetermined frequency from the irradiation device 9 is continued.
On the other hand, in a case where a negative determination is made in S101, next in S104, the irradiation execution flag is off. That is, the irradiation of the microwave from the irradiation device 9 is stopped. If an affirmative determination is made in S102, that is, if the predetermined irradiation execution condition is satisfied but the sampling period is currently set, then in S104, the irradiation execution flag is also turned off. Therefore, the irradiation of the microwave from the irradiation device 9 is stopped. When the present routine was executed last time, if a negative determination is made in S101 or if an affirmative determination is made in S102, the stop of the microwaves from the irradiation device 9 is continued.
According to the above-described flow, even when the predetermined irradiation execution condition is satisfied, the irradiation of the microwave from the irradiation device 9 is stopped during the sampling period.
(modification 1)
Next, a modified example of the microwave irradiation control from the irradiation device to the filter according to the present embodiment will be described. Fig. 4 is a time chart showing transitions of the sampling flag, the irradiation execution flag, the output value Sout1 of the first temperature sensor, and the output value Sout2 of the second temperature sensor when the predetermined irradiation execution condition of the first modification is satisfied.
In the microwave irradiation control according to the present modification, the irradiation of the microwave from the irradiation device 9 is also stopped during the sampling period ds. However, in this modification, as shown in fig. 4, in each sampling period ds, the irradiation execution flag is turned from on to off before the sampling flag is turned from off to on. In each sampling period ds, the irradiation execution flag is switched from off to on after the sampling flag is switched from on to off.
Thus, the irradiation of the microwave from the irradiation device 9 is stopped before the sampling period ds starts, and the irradiation of the microwave from the irradiation device 9 is restarted after the sampling period ds ends. That is, the irradiation stop period of the microwave from the irradiation device 9 is longer than the sampling period ds.
Here, as described above, when the irradiation execution flag is turned off from on during execution of microwave irradiation from the irradiation device 9, irradiation of microwaves from the irradiation device 9 is stopped. When the irradiation execution flag is turned on from off while the irradiation of the microwaves from the irradiation device 9 is stopped, the irradiation of the microwaves from the irradiation device 9 is restarted. However, at this time, the timing of stopping the microwave irradiation or the timing of restarting the microwave irradiation may vary due to a variation in control of the irradiation device 9. Further, as shown in fig. 2, if the timing of switching the on/off of the irradiation execution flag is set in advance so that the length of the irradiation stop period of the microwave from the irradiation device 9 is equal to the length of the sampling period ds, the microwave may be irradiated from the irradiation device 9 during the sampling period ds when the irradiation stop timing of the microwave or the irradiation resumption timing of the microwave varies. That is, it is possible to continue irradiation of the microwaves from the irradiation device 9 even after the sampling period ds starts, or to restart irradiation of the microwaves from the irradiation device 9 before the sampling period ds ends.
Therefore, in the present modification, as shown in fig. 4, the timing of switching between on and off of the irradiation execution flag is set in advance so that the irradiation stop period of the microwave from the irradiation device 9 is longer than the sampling period ds. Thus, even if the timing of stopping the microwave irradiation or the timing of restarting the microwave irradiation varies due to a variation in the control of the irradiation device 9, it is possible to suppress the microwave irradiation during the sampling period ds. Therefore, in the sampling period ds, it is possible to suppress the microwaves from reaching the first temperature sensor 13 and the second temperature sensor 14 with a higher probability.
In the present modification, the length of the interval between the timing when the sampling flag is turned off and the timing when the irradiation execution flag is turned off and the length of the interval between the timing when the sampling flag is turned off and the timing when the irradiation execution flag is turned on and the off are predetermined. Therefore, even in the case of the present modification, the irradiation of the microwaves from the irradiation device 9 can be stopped at a cycle corresponding to a predetermined sampling cycle.
(modification 2)
Fig. 5 is a time chart showing transition of the sampling flag, the irradiation execution flag, and the temperature of the filter 8 (filter temperature) when the predetermined irradiation execution condition is satisfied in the second modification. In the microwave irradiation control according to the present modification, the irradiation of the microwave from the irradiation device 9 is also stopped during the sampling period ds. However, in the present modification, when the predetermined irradiation execution condition is satisfied, the predetermined sampling period is set to be longer in a state where the length of the sampling period ds is made the same as compared to when the predetermined irradiation execution condition is not satisfied.
Here, in the sampling flag and the irradiation execution flag of fig. 5, the broken line indicates the transition of each flag when the predetermined sampling period Cs is set to the same length as when the predetermined irradiation execution condition is not satisfied. In the sampling flag and the irradiation execution flag of fig. 5, the solid line indicates the transition of each flag when the predetermined sampling period Cs' is set to a time length longer than the predetermined irradiation execution condition. In the filter temperature of fig. 5, a broken line L3 indicates a change in the filter temperature when the predetermined sampling period Cs is set to the same length as when the predetermined irradiation execution condition is not satisfied. In the filter temperature of fig. 5, a solid line L4 represents a transition of the filter temperature when the predetermined sampling period Cs' is set to be longer than the predetermined irradiation execution condition.
Here, each time the irradiation of the microwave from the irradiation device 9 is stopped during the sampling period ds, the irradiation of the microwave is repeatedly stopped. In this case, if the frequency of stopping the microwave irradiation is too high, the temperature increase rate of the filter 8 may be decreased. When the temperature increase rate of the filter 8 decreases, the time when the temperature of the filter 8 reaches the predetermined PM oxidation temperature becomes later.
Therefore, in the present modification, as shown in fig. 5, when the predetermined irradiation execution condition is satisfied, the predetermined sampling period is set to be longer in a state where the length of the sampling period ds is the same as compared to when the predetermined irradiation execution condition is not satisfied. Thus, when the irradiation of the microwave from the irradiation device 9 is performed, the interval between the sampling period and the next sampling period becomes longer than when the irradiation of the microwave is not performed. In response to this, the interval between the irradiation stop period of the microwave from the irradiation device 9 and the next irradiation stop period becomes longer. Therefore, even when the predetermined irradiation execution condition is satisfied, the frequency of stopping the irradiation of the microwaves from the irradiation device 9 can be reduced as compared with the case where the sampling period is the same as when the predetermined irradiation execution condition is not satisfied. In this way, as shown by the solid line L4 in fig. 5, even when the predetermined irradiation execution condition is satisfied, the temperature increase rate of the filter 8 can be increased as compared with the case where the sampling period is the same as when the predetermined irradiation execution condition is not satisfied (the broken line L3). Therefore, it is possible to suppress a delay in the timing at which the temperature of the filter 8 reaches the predetermined PM oxidation temperature.
In the present modification, when the predetermined irradiation execution condition is satisfied, the irradiation of the microwave from the irradiation device 9 may be stopped before the sampling period ds is started, and the irradiation of the microwave from the irradiation device 9 may be restarted after the sampling period ds is ended, as in the second modification described above.
(modification 3)
Fig. 6 is a time chart showing transitions of the sampling flag, the irradiation execution flag, the output value Sout1 of the first temperature sensor, and the output value Sout2 of the second temperature sensor when the predetermined irradiation execution condition is satisfied in the third modification. Here, in the above-described embodiment, as shown in fig. 2, irradiation of the microwave from the irradiation device 9 to the filter 8 is stopped every sampling period. In contrast, in the present modification, the irradiation of the microwave from the irradiation device 9 to the filter 8 is stopped in one sampling period of a predetermined plurality of sampling periods.
Fig. 6 illustrates a time chart when the irradiation of microwaves from the irradiation device 9 to the filter 8 is stopped in the primary sampling period ds3 among the tertiary sampling periods ds1, ds2, and ds 3. In this case, the irradiation of the microwave from the irradiation device 9 to the filter 8 is continued in the secondary sampling periods ds1 and ds2 among the tertiary sampling periods. Therefore, in the sampling periods ds1 and ds2, the output value Sout1 of the first temperature sensor 13 and the output value Sout2 of the second temperature sensor 14 fluctuate due to the influence of the microwaves. As a result, in the sampling periods ds1 and ds2, an error occurs between the output value Sout1 of the first temperature sensor 13 and the actual temperature (L1) of the inflowing exhaust gas, and an error occurs between the output value Sout2 of the second temperature sensor 14 and the actual temperature (L2) of the outflowing exhaust gas.
However, in the sampling period ds3 in which the irradiation of the microwave from the irradiation device 9 to the filter 8 is stopped, the occurrence of fluctuations in the output values of the first temperature sensor 13 and the second temperature sensor 14 can be suppressed. Therefore, in the sampling period ds3, the output value of the first temperature sensor 13 indicates the actual temperature of the inflowing exhaust gas (L1), and the output value of the second temperature sensor 14 indicates the actual temperature of the outflowing exhaust gas (L2).
According to the microwave irradiation control of the present modification, the frequency of stopping the irradiation of the microwaves from the irradiation device 9 can be reduced as compared with the case where the irradiation of the microwaves from the irradiation device 9 to the filter 8 is stopped every sampling period. Therefore, the temperature increase rate of the filter 8 can be increased as compared with the case where the irradiation of the microwave from the irradiation device 9 to the filter 8 is stopped every sampling period. Therefore, it is possible to suppress a delay in the timing at which the temperature of the filter 8 reaches the predetermined PM oxidation temperature.
In the present modification, the ECU10 obtains, as the detection values detected by the sensors 13 and 14, the output values of the first temperature sensor 13 and the second temperature sensor 14 sampled during one sampling period (ds 3 in fig. 6) in which the irradiation of the microwave from the irradiation device 9 to the filter 8 is stopped, among the predetermined plurality of sampling periods. The ECU10 estimates the temperature of the filter 8 based on the detection value described above. In other words, the output values of the first temperature sensor 13 and the second temperature sensor 14, which are sampled during the sampling period (ds 1, ds2 in fig. 6) in which the irradiation of the microwave from the irradiation device 9 to the filter 8 is continued, of the predetermined multiple sampling periods, are not used as the detection values of the temperature of the inflowing exhaust gas and the temperature of the outflowing exhaust gas for the temperature estimation of the filter 8 by the ECU 10.
Thus, in the present modification, the output value of the first temperature sensor 13 and the output value of the second temperature sensor 14, which are not affected by the microwave, are also acquired as the detection values detected by the respective sensors 13 and 14. By estimating the temperature of the filter 8 based on the detection value, it is possible to suppress a decrease in accuracy of temperature estimation of the filter 8.
In the present modification, when the irradiation of the microwave from the irradiation device 9 is stopped during the sampling period, the irradiation of the microwave from the irradiation device 9 may be stopped before the sampling period is started and the irradiation of the microwave from the irradiation device 9 may be restarted after the sampling period is ended, as in the second modification described above.
(other modification example)
In the above, the case where the microwave is irradiated from the irradiation device 9 for the purpose of heating the filter 8 is described. However, the purpose of the microwave irradiation from the irradiation device 9 is not limited to the heating of the filter 8. For example, the irradiation device 9 may be provided upstream of the oxidation catalyst 7, and the microwave irradiation from the irradiation device 9 may be performed to heat the oxidation catalyst 7. At this time, when the microwaves irradiated from the irradiation device 9 toward the oxidation catalyst 7 reach the first temperature sensor 13 and/or the second temperature sensor 14, the microwave irradiation control of the above-described embodiment or modification may be applied.
The purpose of the irradiation of the electromagnetic wave from the irradiation device to the exhaust gas purification device according to the present invention is not limited to the heating of the exhaust gas purification device. For example, a selective reduction type NOx catalyst that reduces NOx in exhaust gas using ammonia as a reducing agent may be provided as an exhaust gas purification apparatus in an exhaust passage of an internal combustion engine. In this case, the irradiation device may irradiate the NOx selective reduction catalyst with microwaves for the purpose of estimating the amount of ammonia adsorbed in the NOx selective reduction catalyst. In this case, the irradiation control according to the present invention can be applied to the case where some kind of exhaust gas sensor is provided in the irradiation range of the microwave from the irradiation device.

Claims (7)

1. An exhaust gas purification system for an internal combustion engine, comprising:
an exhaust gas purification device provided in an exhaust passage of an internal combustion engine;
an irradiation device that is provided in the exhaust passage and irradiates the exhaust gas purification device with electromagnetic waves of a predetermined frequency;
an exhaust gas sensor disposed in the exhaust passage within an irradiation range of the electromagnetic wave of the irradiation device; and
an irradiation control unit that performs irradiation of the electromagnetic wave from the irradiation device when a predetermined irradiation execution condition is satisfied,
the irradiation control means stops irradiation of the electromagnetic wave from the irradiation device during a sampling period in which the output value of the exhaust gas sensor is sampled even when the predetermined irradiation execution condition is satisfied.
2. The exhaust gas purification system of an internal combustion engine according to claim 1,
the irradiation control means stops irradiation of the electromagnetic wave from the irradiation device before the start of the sampling period, and restarts irradiation of the electromagnetic wave from the irradiation device after the end of the sampling period.
3. The exhaust gas purification system of an internal combustion engine according to claim 1 or 2,
when the sampling of the output value of the exhaust gas sensor is repeatedly performed at a predetermined sampling period, the predetermined sampling period is set longer in a state where the length of the sampling period is made the same when the predetermined irradiation execution condition is satisfied than when the predetermined irradiation execution condition is not satisfied.
4. The exhaust gas purification system of an internal combustion engine according to claim 1 or 2,
when the sampling of the output value of the exhaust gas sensor is repeatedly performed at a predetermined sampling cycle when the predetermined irradiation execution condition is satisfied, the irradiation control means stops irradiation of the electromagnetic wave from the irradiation device in one of the predetermined plurality of sampling periods.
5. The exhaust gas purification system of an internal combustion engine according to claim 1 or 2,
the exhaust gas sensor is a temperature sensor that detects the temperature of the exhaust gas flowing into the exhaust gas purification apparatus or the exhaust gas flowing out of the exhaust gas purification apparatus.
6. The exhaust gas purification system of an internal combustion engine according to claim 3,
the exhaust gas sensor is a temperature sensor that detects the temperature of the exhaust gas flowing into the exhaust gas purification apparatus or the exhaust gas flowing out of the exhaust gas purification apparatus.
7. The exhaust gas purification system of an internal combustion engine according to claim 4,
the exhaust gas sensor is a temperature sensor that detects the temperature of the exhaust gas flowing into the exhaust gas purification apparatus or the exhaust gas flowing out of the exhaust gas purification apparatus.
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